The present invention pertains generally to systems and methods for programming and controlling the movements of the probe of a voice coil actuator. More specifically, the present invention pertains to systems and methods for manually inputting operational data into a voice coil actuator to program the movement of its probe. The present invention is particularly, but not exclusively, useful for controlling and programming an actuator probe when a specifically timed sequence of different translational and rotational probe positions are required for a work cycle.
It is well known that voice coil actuators can be used in a variety of applications to precisely and accurately position a work probe. Furthermore, it is well known that voice coil actuators can be very effective for rapidly moving a work probe between predetermined positions on a path and to, thereafter, control the exertion of very small controlled forces by the probe on a work piece. Succinctly stated, voice coil actuators are becoming widely recognized as effective tools for use in the manufacture, inspection, and repair of various products. For example, such voice coil actuators are disclosed and claimed in U.S. Pat. No. 5,175,456 which issued to Neff et al. for an invention entitled xe2x80x9cWorkpiece Transporter,xe2x80x9d and in U.S. Pat. No. 5,685,214 which also issued to Neff et al. for an invention entitled xe2x80x9cActuator for Translational and Rotary Movement,xe2x80x9d both of which are assigned to the same assignee as the present invention.
In order to enhance the flexibility and overall usefulness of a voice coil actuator, it is desirable that the actuator be capable of performing a variety of specified work cycles. Such a capability will, necessarily, require that the probe of the actuator must somehow be moved. In some instances, perhaps the entire actuator may need to be moved as well. In all applications, however, regardless whether the actuator itself is moved or held stationary, it will always be desirable to control the probe as it is moved along an essentially linear path relative to the actuator.
Control of a voice coil actuator probe requires the ability to accurately position the probe in a predetermined spatial orientation at a specified time. Accuracy in this case involves precision in moving the probe both in translation and in rotation as it transitions from one position to another position. Furthermore, due to the wide variety of tasks that can be accomplished by a VCA, there are virtually limitless possibilities for probe movement that may be considered. With this in mind, it would be very desirable to have the ability to customize a work cycle for the actuator probe that is specifically tailored to the accomplishment of the assigned task.
In light of the above, it is an object of the present invention to provide a system and method for programming and controlling an actuator probe with a customized work cycle. Another object of the present invention is to provide a system and a method for programming and controlling an actuator probe wherein work cycles can be customized to include a plurality of sequentially timed probe positions. Still another object of the present invention is to provide a system and a method for programming and controlling the movement of an actuator probe between various positions on a path, wherein each position is characterized by translational and rotational locations, as well as a specified time at each of these locations. Yet another object of the present invention is to provide a system and a method for programming and controlling the movement of an actuator probe that is easy to implement, simple to execute and comparatively cost effective.
In accordance with the present invention, a system for controlling the movement of an actuator probe between predetermined positions on a substantially linear path includes a linear encoder, a rotational encoder, and a clock. More specifically, the encoders are used to respectively determine the translational location (xe2x80x9czxe2x80x9d) and rotational location (xe2x80x9cxcex8xe2x80x9d) of the probe on the path.
The clock is then used to determine the time (xe2x80x9ctaxe2x80x9d) at which the probe arrives at these locations, and the time (xe2x80x9ctdxe2x80x9d) at which the probe departs these locations. The system also includes a control module that is connected to the clock, and to each of the encoders. As envisioned for the present invention, the control module will have a key pad for inputting data that identifies the locations (xe2x80x9czxe2x80x9d and xe2x80x9cxcex8xe2x80x9d) and the times (xe2x80x9ctaxe2x80x9d and xe2x80x9ctdxe2x80x9d) for each position of the probe. Further, data can be input for a plurality of sequential positions so that, collectively, the data will establish a work cycle for the probe. The control module will also have a display for providing visual presentations of this data.
In order to establish a work cycle for the actuator probe, a reference time (t0) is set for the clock, and a base datum (which includes both z0 and xcex80) is set for the position of the probe. Next, a first position (i.e. start position) for the work cycle is identified. This is accomplished by using the control module to input a translation location (z1) and a rotation location (xcex81) for the probe at the start time (td1). A second position (z2, xcex82, ta2, td2) can then be sequentially identified for the work cycle.
It is important to note that for a general motion of the probe between the first position and the second position (i.e. one involving both translation and rotation), z2 will change from z1, and xcex82 will change from xcex81 (z2xe2x89xa0z1, and xcex82xe2x89xa0xcex81). For a pure translational movement of the probe, however, (i.e. one where there is no rotation) z2 will be different than z1, but xcex82 will remain equal to xcex81 (z2xe2x89xa0z1 but xcex82 =xcex81). On the other hand, for a pure rotation of the probe between the first position and the second position, z2 will be the same as z1 but xcex8 will change (z2=z1 and xcex82xe2x89xa0xcex81). All of these are possible changes from the first position to the second position and, in each case, the transition is accomplished by using the key pad of the control module to input the appropriate data.
Once the second position for the probe is established with an arrival time ta2, a third position (established at ta3), a fourth position (established at ta4), and so on to an nth position (established at tan) can be sequentially determined for the probe (ta1,a2,a3 . . . an; z1,2,3 . . . n; xcex81,2,3 . . . n; and td1,d2,d3 . . . dn;). Collectively, the sequence of these various positions will then define a work cycle for the probe.
In another aspect for the present invention, it is to be noted that the time duration of both dwell times and transit times for the probe can be programmed into the work cycle by properly selecting input data. Specifically, the dwell time of the probe at a particular position (tdwell) will be the difference between ta and td for the position. Similarly, the duration of a transit time for the probe as it moves between sequentially adjacent positions (ttransit) will be the difference between td at the previous position and the ta at the next immediately subsequent position. Further, it is to be appreciated that by appropriately inputting a xcex94z (e.g. z2xe2x88x92z1), and a xcex94xcex8 (e.g. xcex82xe2x88x92xcex81), together with an appropriate transit time (ttransit) between the positions, the response speed of the actuator probe can be established. In this case the translational speed will be xcex94z /ttransit and the rotational speed will be xcex94xcex8/ttransit.